Basic address options

Addresses are defined in [address_<address>] sections. <address> is just an identifier and can be whatever you want. In this example client_local is arbitrarily chosen as type for the address:


Addresses belong to one of these categories:

  • mac – uses MAC address from client request as part of address
  • id – uses ID given to client in configuration file or database as one octet of address, should be in range 0-FFFF
  • range – generate addresses of given ranges
  • random – created randomly
  • fixed – use only fixed addresses from client configuration
  • dns – get address from DNS

These will discussed in the following paragraphs.

Every address definition therefore needs an category option and a pattern option for its automatic generation. The dynamic part of the address is represented by a placeholder referring to the category and enclosed by $:

category = some_category
pattern = 2001:db8::$some_category$

If an address should include the client MAC address transformed into 3 octets like 01:02:03:04:05:06 to fd00::0102:0304:0506 it belongs to category mac. Its definition is:

category = mac
pattern = fd00::$mac$

If clients have some IDs configured as attribute this ID can be used in the address. A client with ID 1000 will get the address 2001:db8::1000 when category id is defined like this:

category = id
pattern = 2001:db8::$id$

Addresses can be given in ranges too. If this option is used there is an extra option range that defines one. Ranges can range from 0-FFFF and form the last octet of an IPv6 address. Addresses from this example range from 2001:db8::1000 to 2001:db8::1fff.

category = range
range = 1000-1fff
pattern = 2001:db8::$range$

As privacy measure clients can get random addresses. At the moment the generated random part takes the whole 64 bit of the host identifier part of the address. Therefore the placeholder for category random is $random64$ – there might be shorter ones in the future. The resulting address looks like 2001:db8::349a:49f2:9dc2:b3a0.

category = random
pattern = 2001:db8::$random64$

If addresses should not be created dynamically, but fixed, just use the fixed category. Addresses then must be supplied in clients configuration file or database:

category = fixed

If addresses should be managed centrally by your DNS they can be obtained by DNS queries instead of being generated or configured with the dns category. Therefore a nameserver has to be configured in global dhcpy6d options:

category = dns

If the –prefix argument is used when calling dhcpy6d, one can use the $prefix$ variable in a pattern definition, which will be substituted by the given prefix. This might be especially usefull when using changing prefixes given by an ISP:

category = random
pattern = $prefix$::$random64$

Additional options for addresses

Addresses can have these additional options:

  • ia_type
  • preferred_lifetime
  • valid_lifetime
  • dns_update
  • dns_zone
  • dns_rev_zone

IA type of most addresses will be non-temporary – “na”. If temporary addresses are expected to be requested by clients ia_type can be set to temporary “ta”:

ia_type = ta

Addresses will per default have the lifetimes set by general settings, but preferred_lifetime and valid_lifetime can be modified:

preferred_lifetime = 900
valid_lifetime = 1200

If DNS should be updated the flag dns_update has to be set true. At the moment this only works for Bind DNS servers which must be configured in general settings.

dns_update = yes

For DNS updates the zones to update have to be set as configured in DNS. The zone information is set by dns_zone and dns_rev_zone:

dns_zone =
dns_rev_zone =

General settings like used nameserver and credentials are configured in general settings.

©2022 Henri Wahl et al.